Enumerations in PHP

Enumerations in PHP provide a way to define a fixed set of named constants, making your code more readable and preventing invalid values. While older PHP versions required workarounds, PHP 8.1 introduced native enum support.

Native Enums (PHP 8.1+)

PHP 8.1 introduced true enumeration support with the enum keyword

<?php
enum Status {
    case PENDING;
    case APPROVED;
    case REJECTED;
}

function processOrder(Status $status) {
    echo "Order status: " . $status->name . "<br>";
}

processOrder(Status::PENDING);
processOrder(Status::APPROVED);
?>

Order status: PENDING
Order status: APPROVED

Backed Enums

Backed enums allow you to assign specific values to enum cases

<?php
enum Priority: int {
    case LOW = 1;
    case MEDIUM = 2;
    case HIGH = 3;
}

echo "Priority value: " . Priority::HIGH->value . "<br>";
echo "Priority name: " . Priority::HIGH->name . "<br>";

// Convert from value back to enum
$priority = Priority::from(2);
echo "From value 2: " . $priority->name . "<br>";
?>

Priority value: 3
Priority name: HIGH
From value 2: MEDIUM

Legacy Approach: Using Abstract Classes

For PHP versions before 8.1, you can simulate enums using abstract classes

<?php
abstract class Color {
    const RED = "red";
    const GREEN = "green";
    const BLUE = "blue";
}

function setColor($color) {
    echo "Setting color to: " . $color . "<br>";
}

setColor(Color::RED);
setColor(Color::BLUE);
?>

Setting color to: red
Setting color to: blue

Comparison

Conclusion

PHP 8.1+ native enums provide type safety and built-in validation, making them the preferred choice for modern PHP development. For legacy versions, abstract classes with constants offer a workable alternative.